Apparatus and method for distributing power in an HSDPA system

Abstract

A method and an apparatus for redistributing differentiated power for transmitting high speed packet data according to UEs in high speed packet data transport system. The method and apparatus redistribute powers, which have been already assigned in order to transmit the high speed packet data, thereby improving the performance of the system.

Description

PRIORITY[0001]This application claims priority to an application entitled “Apparatus and Method for Distributing Power in HSDPA System” filed in the Korean Industrial Property Office on Jan. 21, 2002 and assigned Ser. No. 2002-3451, the contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates generally to a method and an apparatus for transmitting a high speed packet data in a CDMA mobile communication system, and more particularly to a method and an apparatus for differentiated power distribution in high speed packet transmission.[0004]2. Description of the Related Art[0005]Like other kinds of channels, channels for high speed packet transport employ channelization codes in order to maintain their independence. However, from among channelization codes being used, the channelization codes used by the channels for high speed packet transport utilize shorter codes, that is, codes having smaller...

AI Technical Summary

Benefits of technology

[0017]Accordingly, the present invention has been designed to solve the abovementioned problems occurring in the prior art, and an object of the present invention is to provide a method and an apparatus, which can redistribute powers of UEs having relatively good channel conditions to UEs having relatively bad channel conditions.

[0031]Each MCS level has a predetermined assignment range, which has an upper critical, point and a lower critical point. The same MCS level is given to a UE or UEs having channel conditions between the two critical points. Therefore, a UE having a channel condition slightly exceeding the lower critical point has a higher probability of generating errors, thereby having a higher probability of requiring retransmission, in comparison with another UE having a channel condition adjacent to the upper critical point. In this case, a surplus power of the UE having a relatively good channel condition can be redistributed to the UE having a relatively bad channel condition, so as to improve the communication quality of an entire system. Further, different MCS levels may be given to UEs having similar channel conditions due to only a slight difference between the channel conditions. As a result, a UE or UEs provided with a higher MCS level may have a higher probability of generating errors than a UE or UEs provided with a lower MCS level. In this case, a portion of a power of a UE having a channel condition adjacent to an upper critical point of an MCS level (having a relatively good channel condition) can be redistributed to a UE provided with the same or different MCS level, so as to improve the communication quality of an entire system. In conclusion, the power distribution compensates for the impossibility of and enables precise power control for a UE or UEs even when each MCS level has a broad range in the AMCS. In other words, surplus power of UEs or channels adjacent to the upper critical point of each MCS level can be assigned to UEs or channels adjacent to the lower critical point of the MCS level, so as to realize the precise power control.

[0035]Power can be assigned in consideration of the handover states of UEs. The handover is a phenomenon occurring when an electric field intensity of a currently accessing node B is lower than that of an adjacent node B. It is preferred that a UE in a handover situation as described above carries out the handover after receiving a data packet transmitted from the servicing node B. Therefore, a higher power is assigned to a UE located in a handover area than that assigned to another UE located out of the handover area. This reduces the probability of requiring retransmission of a data packet further to an already transmitted data packet, thereby enabling the handover to be performed after the reception of the data packet is completed. Specifically, power distribution as described above is more often required when the handover is necessary in a retransmission situation. This is because, in order to perform the handover in a situation where the retransmission is necessary, a node B to which a corresponding UE will move should not only information about the corresponding UE but also information in relation to the retransmission.

Problems solved by technology

When a plurality of channelization codes are assigned for a fixed duration as described above, the AMCS cannot effectively use the resources.

That is, although the MCS level is determined corresponding to the channel condition and each of different channelization codes, an optimum channel condition cannot be employed due to the limited MCS levels.

In the conventional transmission apparatus employing the AMCS, since each MCS level has too broad a range, as described above, the same power may be assigned even to UEs having channel conditions which are much different from each other, thereby deteriorating the transport power.

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